Expanding screw



B. F. JACOBS.

EXPANDING SCREW.

APPLICATION man MAY 3. 1920,

12372,@9 1.; Patented Mar. 22, 1921.

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PATENT OFFICE.

BENJAMIN F. JACOBS, OF BOSTON', MASSACHSETTS.

' EXPANDING SCREW.

Specication of Letters Patent.

Patented Mar. 22, 1921.

Application led May 3,` 1920, Serial No. 378,663.'

To all whom it may concern.'

Be it known that I, BENJAMIN F. JACOBS, a citizen of the United States, residing at South Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in EX- panding Screws, of which the following is a specification.

This invention relates to certain new and useful improvements in driven screw threaded fastenings, and it more particularly belongs to that class known as expanding sleeves, the plug in this instance being adapted to enter the same from the lower end.

lith screw threaded fastenings as now constructed one of the disadvantagesy found in practice is to secure a fastener which if it becomes upset or-jammed in its hole, can be readilyaccessible and removable.

One of the objects, I have in view, is to overcome the diiiculty encountered and this I accomplish by constructing my device in such a manner that with the plug used at the bottom end, it rests conjointly upon that part of the machine upon which it is placed, thus co-acting at this point to largely if not entirely obviate the jamming of the screw.

Another object- I have in view is to provide means whereby should it become necessary 'at any time to remove the screw, there will be little or no difficulty in so doing.

Another object of my invention is to construct a device of the character indicated which will .be reliable in use and of eX- tremely simple design sou that it will be capable of easy manufacture by automatic machinery, thus insuring cheap production.

lVith these and other objects in view which may be incident to the use of the improvements, the invention consists of the parts and combinations thereof hereinafter set forth and claimed with the understanding that the several necessary elements conwhich, for the purpose' of explanation have.

been 'made the Subj ect of illustration.

.of constructing the' lower Figure 1 is a sectional view of my device showing the angle between the plug and the eXpansible sleeve.

Fig. 2 is a sectional view on thel line 2 2 of Fig. 1 .showingthe position ofthe plug after it has been driven hdme.

Fig. 3 is a side elevation of my device showing the slots in the top and` bottom thereo Fig. 4 is a. side elevation of the same.

Fig. 5 is a bottom View thereof.

Fig. 6 is a detail plan view of the plug.

The numeral 1 represents a metallic screw, the upper end or face ofwhich, if desired, may be made square or of hexagon' contiguration o-r simply plain as shown in the drawings. A slot iscut across its face as shown at 2, and its lower face is also slotted as shown at 3. The object of the slot at 2 vis to permit of the use of a screw driver to drive the screw intozits proper place. The

slot in the lower face, however, is made somewhat deeper than. the one in the upper face so as to allow for the expansion of the screw as hereinafter more fully appears. Said screw is provided with an interior longitudinal bore 5, which at its lower portion is tapered as shown at 6 to form a conical seat.

The numeral 10 refers to a. plug, the up per end of which terminates in Aa tit 11, adapted to fit closely in cross sectlon the diameter of the bore, but its lower conical portion 'is widened as at 12 to an angle some- 4whatI greater, say 65 degrees, than the conical recess into which it is adapted to sit, which may be, say degrees. -As a result ortion of the plug of a greater diameter in cross section than its seat, the plug when first lnserted in the screw will bear against the side of the seat unevenly, but when it shall have been driven home, the angles of the two members will approximate each other, the pressure against the conical seat will be much greater than if there were no such an les, and the sides of the screw will fit the c oser against the walls of the hole in which` it is contained.

The object in' having the bore extendientirely through the screw is to permit of the insertion of a tool to reaehthe plug should the screw become jammed.

Vith screws as now constructed. when one becomes upset in its hole. it has been found in practice almost impossible to dislodge it and in an effort to do so. the head not infrequently becomes disrupted rendering it impossible to remove the screw. save by boring it out. A screw constructed. however. as shown in the drawings here-to annexed. can easily be dislodged by the insertion of a small drift or other appropriate too-l through the top of the screw and by giving it a blow. whereupon the plug at the bottom which is jarred somewhat from its angle of pressure against the screw allows the lower end of the latter to contract slightly and renders it more adaptable to be unscrewed readily from the top.

lhile I have herein shown and described the preferred embodiment of my invention. I wish it to be understood that I do not confine myself to the precise details of construction herein set forth by way of illustration, as it is apparent that many modifications and variations ma)` be made therein h v thosey skilled in the art without departingl ilroni the spirit of t ie invention or exceedin; r the scope ot' the appended claim.

l claim .ln expanding-` screw comprising` an externally threaded bodv whose upper end is provided with means for receiving" an open ating tool and whose interior is provided with a central longitudinal bore terminat- ;ng at its lower end in a conical seat. a plugY having a cylindrical part and a conical parl idapted to enter and bear against .said seat. the angle of the plug being' inade gri-eater :han that or' the seat so that the angles olIY the pluf r and seat will more nearl \v approximate each other as the screw is driven hoine.

n testimony whereof l alii); niv signature.

BENJAMIN F. JACOBS. 

